Historical context is important here. The breast was seen as the seat of the heart in the ancient Greek world, hence why some descriptions of emotions are described as coming from the breast. Likewise, when the Greek goddesses or other women who are considered to be the ideal of beauty come in, it was natural that their general figure would be described, which included their breasts, so it wasn't Homer pulling his inner G.R.R. Martin. When it comes to battle wounds, which is what I'm assuming you're referring to given the inclusion of nipples, Homer is known for describing realistic battle wounds, and seeing that most of the armor of the time left people open on the side of the chest near the armpits, it would make sense that most wounds would come in the breast/nipple area.